U.S. patent application number 11/548523 was filed with the patent office on 2007-07-05 for polymer resin binder, pigment dispersions, and ink-jet ink for color filter.
This patent application is currently assigned to SAMSUNG ELECTRONICS CO., LTD.. Invention is credited to Yoon-doe JONG, In-seo KEE, Seong-jin KIM, Jung-yong LEE, Chun YOON.
Application Number | 20070155856 11/548523 |
Document ID | / |
Family ID | 38293106 |
Filed Date | 2007-07-05 |
United States Patent
Application |
20070155856 |
Kind Code |
A1 |
KEE; In-seo ; et
al. |
July 5, 2007 |
POLYMER RESIN BINDER, PIGMENT DISPERSIONS, AND INK-JET INK FOR
COLOR FILTER
Abstract
Provided is a polymer resin binder included in an inkjet ink for
a color filter which is manufactured by polymerizing multiple types
of functional monomer including: a monomer having an affinity for
the pigment; a monomer having high mechanical strength; or a
monomer having an affinity for a solvent, and contains an amine
based organic material. Accordingly, the polymer resin, binder for
forming inkjet ink for a color filter can improve a dispersion
property and dispersion stability and an ejection property and
ejection stability of inkjet ink.
Inventors: |
KEE; In-seo; (Gyeonggi-do,
KR) ; YOON; Chun; (Seoul, KR) ; JONG;
Yoon-doe; (Seoul, KR) ; LEE; Jung-yong;
(Seoul, KR) ; KIM; Seong-jin; (Gyeonggi-do,
KR) |
Correspondence
Address: |
CANTOR COLBURN, LLP
55 GRIFFIN ROAD SOUTH
BLOOMFIELD
CT
06002
US
|
Assignee: |
SAMSUNG ELECTRONICS CO.,
LTD.
Gyeonggi-do
KR
|
Family ID: |
38293106 |
Appl. No.: |
11/548523 |
Filed: |
October 11, 2006 |
Current U.S.
Class: |
523/160 ;
523/161 |
Current CPC
Class: |
C09D 11/30 20130101 |
Class at
Publication: |
523/160 ;
523/161 |
International
Class: |
C09D 11/00 20060101
C09D011/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 30, 2005 |
KR |
10-2005-0135847 |
Claims
1. A polymer resin binder of inkjet ink for a color filter
comprising a polymer of multiple types of functional monomer,
wherein the polymer resin binder contains an amine based organic
material represented by Formula 1: [--NH.sub.xR.sub.y], Formula 1
where R is a C.sub.1-20 alkyl group, a C.sub.1-10 alkoxy group, a
C.sub.6-20 aryl group, a C.sub.6-10 aryloxy group, a C.sub.2-20
alkenyl group, a C.sub.7-40 alkyl aryl group, a C.sub.7-40
arylalkyl group, a C.sub.8-40 arylalkenyl group, or a C.sub.2-10
alkynyl group; and x is 0 to 2, y is 1 to 3, and x+y=3.
2. The polymer resin binder of claim 1, wherein the functional
monomer comprises: (a) styrene or benzyl methacrylate; and (b)
methacrylic acid, acrylic acid, methacrylamide, or acrylamide.
3. The polymer resin binder of claim 1, wherein the amine based
organic material is at least one selected from the group consisting
of aniline, N-alkylaniline, 2-ethylhexylamine, triethylamine,
pentyl amine, n-hexylamine, p-aminobenzoic acid, pyrrolidine,
pyrimidine, morpholine, pyridine, piperazine, and quinoline.
4. The polymer resin binder of claim 1, wherein the amine based
organic material is 0.1-30 weight % based on 100 weight % of the
total of (a) and (b).
5. The polymer resin binder of claim 1, wherein when the molar
content of (a) is 0.3 to 5, the molar content of (b) is 0.3 to 5,
based on the molar ratio of (a) and (b).
6. The polymer resin binder of claim 1, wherein the functional
monomer further comprises (c) methacrylate having a C.sub.1-5 alkyl
group or 2-hydroxy ethyl group.
7. The polymer resin binder of claim 6, wherein the content of the
amine based organic material is 0.1 to 30 weight % based on 100
weight % of the total of (a), (b), and (c).
8. The polymer resin binder of claim 6, wherein when the molar
content of (a) is 0.3 to 3.0, the molar content of (b) is 0.2 to
2.5, and the molar content of (c) is 0.3 to 3.0, based on the molar
ratio of (a), (b), and (c).
9. The polymer resin binder of claim 1, wherein the amine based
organic material is in a physically bonded state.
10. The polymer resin binder of claim 1, wherein the amine based
organic material is in a chemically bonded state.
11. A pigment dispersion included in an inkjet ink for a color
filter comprising a pigment, a dispersion agent, a surfactant, and
the polymer resin binder of claim 1.
12. The pigment dispersion of claim 11, wherein the surfactant is a
fluoric surfactant.
13. The pigment dispersion of claim 11, wherein the pigment is at
least one selected from the group of pigments consisting of red
254, red 177, blue 15:6, green 36, yellow 150, yellow 139, yellow
138, and violet 23.
14. The pigment dispersion of claim 11, wherein the content of the
polymer resin binder is 20-150 weight % based on 100 weight % of
the total pigment.
15. The pigment dispersion of claim 11, wherein the content of the
dispersion agent is 0.1-30 weight % based on 100 weight % of the
total pigment, and the content of the surfactant is 0.01-2 weight %
based on 100 weight % of the total pigment.
16. An inkjet ink for a color filter comprising the pigment
dispersion of claim 11.
17. A pigment dispersion included in an inkjet ink for a color
filter comprising at least two polymer resin binders of claim 1,
and further comprising a pigment, a dispersion agent, and
surfactant with the binder mixture.
18. The pigment dispersion of claim 17, wherein the surfactant is a
fluoric surfactant.
19. The pigment dispersion of claim 17, wherein the pigment is at
least one selected from the group of pigments consisting of red
254, red 177, blue 15:6, green 36, yellow 150, yellow 139, yellow
138, and violet 23.
20. The pigment dispersion of claim 17, wherein the content of the
binder mixture is 20-150 weight % based on 100 weight % of the
total pigment.
21. The pigment dispersion of claim 17, wherein the content of the
dispersion agent is 0.1-30 weight % based on 100 weight % of the
total pigment, and the content of the surfactant is 0.01-2 weight %
based on 100 weight % of the total pigment.
22. An inkjet ink for a color filter comprising the pigment
dispersion of claim 17.
23. A method of manufacturing a polymer resin binder of inkjet ink
for a color filter comprising polymerizing multiple types of
functional monomer, wherein the polymer resin binder comprises an
amine based organic material represented by Formula 1:
[--NH.sub.xR.sub.y], Formula 1 where R is a C.sub.1-20 alkyl group,
a C.sub.1-10 alkoxy group, a C.sub.6-20 aryl group, a C.sub.6-10
aryloxy group, a C.sub.2-20 alkenyl group, a C.sub.7-40 alkyl aryl
group, a C.sub.7-40 arylalkyl group, a C.sub.8-40 arylalkenyl
group, or a C.sub.2-10 alkynyl group; and x is 0 to 2, y is 1 to 3,
and x+y=3.
24. A method of manufacturing a pigment dispersion included in an
inkjet ink for a color filter comprising mixing a pigment, a
dispersion agent, a surfactant, and a polymer resin binder
comprising: an amine based organic material represented by Formula
1: [--NH.sub.xR.sub.y], Formula 1 where R is a C.sub.1-20 alkyl
group, a C.sub.1-10 alkoxy group, a C.sub.6-20 aryl group, a
C.sub.6-10 aryloxy group, a C.sub.2-20 alkenyl group, a C.sub.7-40
alkyl aryl group, a C.sub.7-40 arylalkyl group, a C.sub.8-40
arylalkenyl group, or a C.sub.2-10 alkynyl group; and x is 0 to 2,
y is 1 to 3, and x+y=3.
25. The method of claim 24, wherein the polymer resin binder is
added to the pigment dispersion.
26. The method of claim 24 comprising mixing at least two polymer
resin binders to form a binder mixture, and further mixing a
pigment, a dispersion agent, and surfactant with the binder
mixture.
27. A method of manufacturing an inkjet ink, comprising mixing a
pigment, a dispersion agent, a surfactant, and a polymer resin
binder comprising: an amine based organic material represented by
Formula 1: [--NH.sub.xR.sub.y], Formula 1 where R is a C.sub.1-20
alkyl group, a C.sub.1-10 alkoxy group, a C.sub.6-20 aryl group, a
C.sub.6-10 aryloxy group, a C.sub.2-20 alkenyl group, a C.sub.7-40
alkyl aryl group, a C.sub.7-40 arylalkyl group, a C.sub.8-40
arylalkenyl group, or a C.sub.2-10 alkynyl group; and x is 0 to 2,
y is 1 to 3, and x+y=3.
28. The method of claim 27, wherein during the manufacture of the
inkjet ink the polymer resin binder is added to the pigment
dispersion.
Description
CROSS-REFERENCE TO RELATED PATENT APPLICATION
[0001] This application claims priority to Korean Patent
Application No. 10-2005-0135847, filed on Dec. 30, 2005, and all
the benefits accruing therefrom under 35 U.S.C. .sctn. 119(a), the
contents of which is herein incorporated by reference in its
entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a polymer resin binder
included in an inkjet ink for a color filter, and more
particularly, to a polymer resin binder included in an inkjet ink
for a color filter which can improve a dispersion property and
dispersion stability of the inkjet ink, and an ejection property
and ejection stability of the inkjet ink.
[0004] 2. Description of the Related Art
[0005] Inkjet ink is a useful component for the manufacture of a
color filter, which is one of the main components of a liquid
crystal display device. Inkjet ink is used to form the color filter
provides image realization in a liquid crystal display device. In
the color filter, three colors of inkjet ink of red, blue, and
green, are coated onto a color filter substrate by being sprayed
using an inkjet head, coated, and then thermally hardened.
Accordingly, the inkjet ink forms an ink film, which is a colored
layer, in the color filter.
[0006] The basic structure and operation of a color filter will be
described briefly as follows.
[0007] Light generated from a backlight unit is selectively allowed
to pass through a polarization plate and liquid crystals
sequentially, and the passing light finally passes through a color
filter, thereby forming a color image by combining images of three
colors. Accordingly, the final quality of an image seen by human
eyes is decided by the quality of the color filter, and the quality
of the color filter is decided by the quality and kind of pigment
and additives used in the inkjet ink.
[0008] A colored layer can be formed in a color filter using inkjet
ink as described above or using photosensitive resins.
[0009] The method using an inkjet ink to form a colored layer has
the following advantages over the method using a photosensitive
resin. That is, processes like coating, exposing, and developing
for each color are not required, but instead three colors of red,
green, and blue can be coated at the same time and then hardened,
thereby reducing the number of processes and minimizing waste of
the material and waste of solution. Accordingly, research is also
being conducted for replacing the photosensitive resin used to form
the colored layer of a color filter with inkjet ink.
[0010] Inkjet ink for a color filter includes a pigment dispersion,
a polymer resin binder, a functional monomer, a heat initiator, and
a surfactant. Other additives, and a solvent may also be
included.
[0011] The pigment dispersion, a core element of inkjet ink, is
manufactured from three colors of red, green, and blue pigments
which are dispersed as super corpuscles present in a colloidal
state in a solvent. Accordingly, the super corpuscle in a colloid
state must have good dispersion and the dispersion stability
thereof should not change under any physically or chemically
inappropriate conditions.
[0012] More specifically, the pigment dispersion is manufactured by
mixing a solvent, a dispersion agent, and other additives to a
pigment in an appropriate, predetermined ratio, and then
pulverizing the mixture in a pulverizer. The inkjet ink is then
manufactured by mixing a polymer resin binder, a multifunctional
monomer, an initiator, and other additives with the pigment
dispersion.
[0013] In the manufacture of a pigment dispersion as described
above, the dispersion agent is a polymer type surfactant, and plays
a key role in maintaining a stable disperse system. Also, recently,
as technology in the field of liquid crystal display devices is
developing at a high speed, liquid crystal display devices having
high transmittance, high chromaticity, high brightness, and high
contrast have been realized, and thus the pigment dispersion and
the polymer resin binder need to be improved accordingly.
[0014] That is, in the case of a conventional high transmittance
color filter, the concentration of the pigment does not have to be
high and therefore a large amount of dispersion agent compared to
pigment can be used. When the concentration of the dispersion agent
is high, a good dispersion property and dispersion stability are
thereby maintained. However, as liquid crystal display devices are
being developed, more high chromaticity is required, and for high
chromaticity realization, a large amount of pigment must be present
in the optical path (i.e., must be "stacked") of the color filter,
and the usage of the disperse agent should be reduced in contrast.
Thus, when a small amount of disperse agent is used, the dispersion
property and the dispersion stability of the pigment particle in
the form of a super corpuscle decreases.
[0015] The polymer resin binder is desirably used for manufacturing
both the pigment dispersion and the inkjet ink, and can thus
improve the dispersion property and dispersion stability of the
pigment. Conventional commercialized polymer resin binders mixed
with dispersion agents to manufacture pigment dispersions.
[0016] However, conventional commercialized polymer resin binders
cannot provide sufficient dispersion properties and the dispersion
stability of the pigment.
BRIEF SUMMARY OF THE INVENTION
[0017] The present invention provides, in an embodiment, a polymer
resin binder which can improve a dispersion property and dispersion
stability of a pigment when used to manufacture an inkjet ink for a
color filter of a liquid crystal display device.
[0018] The present invention also provides, in an embodiment, a
polymer resin binder which is used to manufacture an inkjet ink for
a color filter of a liquid crystal display device and which can
improve ink ejection property and ejection stability when ejected
from an inkjet head.
[0019] According to an embodiment of the present invention, there
is provided a polymer resin binder of inkjet ink for a color filter
which comprises a polymer comprising multiple types of functional
monomer, wherein the polymer resin binder contains an amine based
organic material represented by Formula 1 below:
[--NH.sub.xR.sub.y], Formula 1
[0020] where R is a C.sub.1-20 alkyl group, a C.sub.1-10 alkoxy
group, a C.sub.6-20 aryl group, a C.sub.6-10 aryloxy group, a
C.sub.2-20 alkenyl group, a C.sub.7-40 alkyl aryl group, a
C.sub.7-40 arylalkyl group, a C.sub.8-40 arylalkenyl group, a
C.sub.2-10 alkynyl group, or a combination comprising at least one
of the foregoing groups; and x is 0 to 2, y is 1 to 3, and
x+y=3.
[0021] According to an embodiment, the functional monomer may
comprise: (a) styrene or benzyl methacrylate; and (b) methacrylic
acid, acrylic acid, methacrylamide, or acrylamide.
[0022] According to another embodiment, the amine based organic
material may be at least one selected from the group consisting of
aniline, N-alkylaniline, 2-ethylhexylamine, triethylamine, pentyl
amine, n-hexylamine, p-aminobenzoic acid, pyrrolidine, pyrimidine,
morpholine, pyridine, piperazine, and quinoline.
[0023] The amine based organic material may be 0.1-30 weight %
based on 100 weight % of the total of (a) and (b).
[0024] When the content of (a) may be 0.3 to 5, the content of (b)
may be 0.3 to 5, based on the molar ratio.
[0025] The functional monomer may further comprise (c) methacrylate
having a C.sub.1-5 alkyl group or 2-hydroxy ethyl group.
[0026] The content of the amine based organic material may be 0.1
to 30 weight % based on 100 weight % of the total of (a) through
(c).
[0027] When the content of (a) may be 0.3 to 3.0, the content of
(b) may be 0.2 to 2.5, and the content of (c) may be 0.3 to 3.0,
based on the molar ratio.
[0028] According to another embodiment of the present invention,
there is provided a pigment dispersion included in an inkjet ink
for a color filter which comprises a pigment, a dispersion agent, a
surfactant and a polymer resin binder.
[0029] The surfactant may be a fluoric surfactant.
[0030] The pigment may be at least one selected from the group of
pigments consisting of red 254, red 177, blue 15:6, green 36,
yellow 150, yellow 139, yellow 138, and violet 23.
[0031] The content of the polymer resin binder may be 20-150 weight
% based on 100 weight % of the total pigment.
[0032] The content of the dispersion agent may be 0.1-30 weight %
based on 100 weight % of the total pigment, and the content of the
surfactant may be 0.01-2 weight % based on 100 weight % of the
total pigment.
[0033] According to another embodiment of the present invention,
the amine based organic material may be in a physically bonded
state.
[0034] According to another embodiment of the present invention,
the amine based organic material may be in a chemically bonded
state.
[0035] According to another embodiment of the present invention,
there is provided an inkjet ink for a color filter manufactured
using the pigment dispersion.
[0036] According to another embodiment of the present invention,
there is provided a method of manufacturing a polymer resin binder
of inkjet ink for a color filter comprising polymerizing multiple
functional monomers and an amine based organic material.
[0037] According to another embodiment of the present invention,
there is provided a method of manufacturing a pigment dispersion
included in an inkjet ink for a color filter comprising mixing a
pigment, a dispersion agent, a surfactant, and a polymer resin
binder comprising an amine based organic material.
[0038] According to another embodiment of the method, the polymer
resin binder is added to the pigment dispersion. In a further
embodiment, the method of making the pigment dispersion comprises
mixing at least two polymer resin binders to form a binder mixture,
and further mixing a pigment, a dispersion agent, and surfactant
with the binder mixture.
[0039] According to another embodiment of the present invention,
there is provided method of making an inkjet ink, comprising mixing
a pigment, a dispersion agent, a surfactant, and a polymer resin
binder comprising an amine based organic material wherein during
the manufacture of the inkjet ink the polymer resin binder is added
to the pigment dispersion.
[0040] According to an embodiment of the present invention, during
the manufacture of the inkjet ink for a color filter, the polymer
resin binder may be added to the pigment dispersion.
BRIEF DESCRIPTION OF THE DRAWINGS
[0041] The above and other features and advantages of the present
invention will become more apparent by describing in detail
exemplary embodiments thereof with reference to the attached
drawings in which:
[0042] FIG. 1 is a diagram of a basic structure of an exemplary
polymer resin binder according to an embodiment;
[0043] FIG. 2A is a photograph showing the degree of condensation
of conventional inkjet ink not containing an amine based organic
material for a color filter; and
[0044] FIG. 2B is a photograph showing the degree of condensation
of an exemplary inkjet ink containing an amine based organic
material for a color filter according to an embodiment.
DETAILED DESCRIPTION OF THE INVENTION
[0045] The present invention will now be described more fully with
reference to the accompanying drawings, in which exemplary
embodiments of the invention are shown.
[0046] It will be understood that when an element is referred to as
being "on" another element, it can be directly on the other element
or intervening elements may be present therebetween. In contrast,
when an element is referred to as being "disposed on" another
element, the elements are understood to be in at least partial
contact with each other, unless otherwise specified.
[0047] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the invention. As used herein, the singular forms "a", "an" and
"the" are intended to include the plural forms as well, unless the
context clearly indicates otherwise. It will be further understood
that the terms "comprises" and/or "comprising," or "includes"
and/or "including" when used in this specification, specify the
presence of stated features, regions, integers, steps, operations,
elements, and/or components, but do not preclude the presence or
addition of one or more other features, regions, integers, steps,
operations, elements, components, and/or groups thereof.
[0048] Unless otherwise defined, all terms (including technical and
scientific terms) used herein have the same meaning as commonly
understood by one of ordinary skill in the art to which this
invention belongs. It will be further understood that terms, such
as those defined in commonly used dictionaries, should be
interpreted as having a meaning that is consistent with their
meaning in the context of the relevant art and the present
disclosure, and will not be interpreted in an idealized or overly
formal sense unless expressly so defined herein.
[0049] Thus, a polymer resin binder comprises a plurality of
functional monomers and contains an amine based organic material
represented by Formula 1 below. The polymer resin binder included
in an inkjet ink for a color filter, wherein the polymer is
manufactured by polymerizing a plurality of monomers, contains an
amine based organic material represented by Formula 1 below:
[--NH.sub.xR.sub.y], Formula 1
[0050] where R is a C.sub.1-20 alkyl group, a C.sub.1-10 alkoxy
group, a C.sub.6-20 aryl group, a C.sub.6-10 aryl oxy group, a
C.sub.2-20 alkenyl group, a C.sub.7-40 alkyl aryl group, a
C.sub.7-40 aryl alkyl group, a C.sub.8-40 aryl alkenyl group, a
C.sub.2-10 alkynyl group, or a combination comprising at least one
of the foregoing groups; and x is 0 to 2, y is 1 to 3, and
x+y=3.
[0051] The polymer resin binder can be added to the pigment when
the pigment dispersion is manufactured, added to the pigment
dispersion when the inkjet ink is manufactured, or added in both
processes. Accordingly, the polymer resin binder affects the
properties of the pigment dispersion and the inkjet ink which
contains the polymer resin binder.
[0052] Generally, inkjet ink must have a good dispersion property
and dispersion stability, a good ejection property and ejection
stability, high transparency, good chemical resistance, good
mechanical durability, and high chromaticity realization.
[0053] To satisfy the above properties of the inkjet ink, the
properties of the polymer resin can be adjusted.
[0054] For this, a polymer having a functional monomer comprising
not one type monomer but multiple types of monomer is used.
[0055] FIG. 1 is a diagram of a basic structure of monomers used in
a polymer resin binder according to an embodiment.
[0056] The combination of monomers provides desired properties.
Referring to FIG. 1, a monomer having an affinity for the pigment,
a monomer having high mechanical strength, and a monomer having an
affinity for the solvent are combined in combinations possessing
two or three of the foregoing desired properties, to be used as the
functional monomer. Thus, the synthesized polymer resin binder is
useful with various kinds of pigments, thereby improving the low
viscosity dispersion property and dispersion stability of the
pigment dispersion and inkjet ink.
[0057] As an example of the functional monomer, two kinds of
monomers can be combined to be used as a functional monomer, such
as monomer (a) having an affinity for the pigment and monomer (b)
having an affinity for the solvent. In an embodiment, when the
molar content of monomer (a) is of 0.3 to 5, the molar content of
monomer (b) is 0.3 to 5 based on the molar ratio (a) and (b).
[0058] As another example of the functional monomer, three types of
monomer can be combined to be used as a functional monomer, such as
monomer (a) having an affinity for the pigment, monomer (b) having
an affinity for the solvent, and monomer (c) having good mechanical
strength. In this case, the molar content of monomer (a) may be 0.3
to 3.0, the molar content of monomer (b) may be 0.2 to 2.5, and the
molar content of monomer (c) may be 0.3 to 3.0, based on the molar
ratio of (a), (b), and (c).
[0059] Monomer (a) has an affinity for a pigment. More
particularly, monomer (a) has an affinity for a benzene or alkyl
group of the pigment, and may be styrene, benzyl methacrylate,
2-ethylhexyl methacrylate, or 2-ethylhexylacrylate, and the
like.
[0060] Monomer (b) having an affinity for a solvent may be
methacrylic acid, acrylic acid, methacrylamide, acrylamide, and the
like.
[0061] Also, monomer (c) having good mechanical strength may be
methacrylate including a C.sub.1-5 alkyl group or 2-hydroxy ethyl
group, or butyl acrylate, and the like.
[0062] The monomers used in the present invention are not limited
to these, and various commercially usable monomers such as methyl
methacrylate, glycidyl methacrylate, and the like, can be used. Of
these monomers, glycidyl methacrylate can provide a copolymer with
higher hardness and improved chemical resistance due to epoxy
cross-linkage during thermal hardening. Accordingly, in an
exemplary embodiment, glycidyl methacrylate is useful for the
manufacture of an inkjet ink for a color filter.
[0063] The relative molar ratio and kinds of functional monomers
used may vary according to the desired properties of the copolymer.
Specifically, the optimum useful molar ratios and kinds of the
monomers must be decided in consideration of the degree of the
polarity of the pigment, desired viscosity, and the characteristics
of the solvent to be used.
[0064] A solvent is used in the synthesis of the polymer resin
binder, of which protic and aprotic solvents except water can be
used as the solvent. Examples of protic solvents include butyl
alcohol, isopropyl alcohol, and ethyl alcohol. Examples of aprotic
solvents include propylene glycol monomethyl ether acetate
("PGMEA"), dipropylene glycol methyl ether acetate, diethylene
glycol monobutyl ether acetate, diglyme, and the like. However,
aprotic solvents that have less reactivity than protic solvents are
preferable for use for the manufacture of a polymer resin binder
included in an inkjet ink for a color filter. Also, when a polymer
resin binder is synthesized in the aprotic solvent, separation of
the solvent from the polymer resin can be omitted, and is thus
advantageous for reducing the number of manufacturing process
operations.
[0065] The polymer resin binder contains an amine based organic
material represented by Formula 1. Also, in an embodiment, the
content of amine based organic material is 0.1-30 weight %,
specifically 1-10 weight % based on 100 weight % of the total
functional monomer.
[0066] The amine based organic material can be added when the
polymer resin binder is synthesized or separately added after the
polymer resin binder is polymerized. The amine based organic
material can stabilize the particles of the dispersion by adjusting
the degree of acidity and basicity of the organic acid or the amine
based organic material that is included in the polymer resin binder
or the pigment dispersion and can prevent ink aggregation when the
inkjet ink is dried. Here, the amine based organic material can
combine with the organic acid or the amine based organic material
physically and/or chemically.
[0067] The mechanism of the dispersion stabilization of the pigment
dispersion is as follows.
[0068] When water is used as a solvent, the pigment particles are
dispersed by the anionic electrostatic repulsion of carboxyl groups
(such as those introduced to the polymer resin binder by a
carboxylic acid monomer, e.g., methacrylic acid) included in the
polymer resin binder, which surrounds the pigment particles. In
contrast, when an organic solvent is used, the pigment particles
are dispersed by the steric hindrance effect of the polymer resin
binder which surrounds the pigment particles. When an organic
solvent is used, it is not necessary to introduce anions, but
carboxyl acid group of methacrylic acid or acrylic acid, or amide
group in methacrylamide or acrylamide in the structure of the
pigment dispersion has an affinity for a protic or a polar aprotic
organic solvent due to a hydrogen bond, thereby becoming stable.
The pigments surrounded by the polymer resin binder or dispersion
agent are blocked from interacting each other by the steric
hindrance effect, thereby increasing the dispersion stability.
[0069] Basically, univalent, divalent, or trivalent amine can be
used as the amine based organic material, and if soluble in the
organic solvent, C.sub.5-20 aliphatic amine, heterocyclic amine, or
amine having a benzene ring can be used.
[0070] Specifically, the amine based organic material can be at
least one material selected from the group consisting of aniline,
an N-alkylaniline, 2-ethylhexylamine, triethylamine, pentyl amine,
n-hexylamine, p-aminobenzoic acid, pyrrolidine, pyrimidine,
morpholine, pyridine, piperazine, and quinoline.
[0071] Furthermore, the polymer resin binder desirably has an
appropriate molecular weight for inclusion in the inkjet ink for a
color filter. The weight averaged molecular weight (Mw) thereof may
be 1,000 to 100,000 g/mol, specifically 5,000 to 50,000 g/mol, and
more specifically 10,000 to 20,000 g/mol. Generally the molecular
weight of a polymer can be from more than hundreds of thousands to
millions, but it is advantageous that the molecular weight of a
polymer resin binder which is to have a low viscosity be small.
That is, a polymer resin binder having a low molecular weight can
be used in circumstances in which low viscosity is useful, such as
a photosensitive resin for a color filter or an inkjet ink for a
color filter.
[0072] The molecular weight of the polymer resin binder during
synthesis is adjusted by reaction conditions, that is, the
concentration of the functional monomer, the reaction temperature,
and the amount of the initiator. For example, when the
concentration of the functional monomer and the reaction
temperature are high and the amount of the initiator used is large,
the molecular weight is reduced.
[0073] Thus, a method of manufacturing the polymer resin binder of
inkjet ink for a color filter comprises polymerizing multiple types
of functional monomers and an amine based organic material. When
the polymer resin binder is synthesized, the total amount of the
functional monomer is 5-60 weight %, specifically 10-40 weight %,
and more specifically 15-30 weight % based on 100 weight % of the
total reaction material (i.e., monomer, solvent, and initiatior).
The reaction temperature for the synthesis of the polymer resin
binder may be 50-120.degree. C., specifically 60-100.degree. C.,
more specifically 70-90.degree. C.
[0074] Free radical polymerization initiators may be used to
polymerize the monomers, such as, for example, peroxy initiators,
diazo initiators, and the like. An exemplary reaction initiator is
2,2'-azobisisobutyronitrile ("AIBN"). The reaction initiator can be
used in an amount of 0.1-10 weight %, specifically 0.5-5 weight %,
and more specifically 2-4 weight %, based on 100 weight % of the
total functional monomer.
[0075] The polymer resin binder comprises a random type polymer and
has an excellent dispersion effect characteristic. The synthesized
polymer resin binder, either having the solvent removed or
including the solvent, can be mixed with an appropriate amount of
pigment and pulverized using various kinds of pulverizers.
Generally, the polymer resin binder used can be present in an
amount of 20 to 150 weight % based on 100 weight % of the total
pigment, though the amount may vary depending on the type of
pigment used. Also, the polymer resin binder can be applied
directly to the next process without separating the solvent from
the polymer resin binder when synthesized in an aprotic
solvent.
[0076] Hereinafter, synthesis methods for forming the polymer resin
binder according to the purpose of usage will be described in
detail.
[0077] In a first exemplary embodiment, the synthesis of a polymer
resin binder having a basic structure which can be included in
inkjet ink for a color filter will be described.
[0078] First, benzyl methacrylate, methyl methacrylate, and
methacrylic acid are mixed properly with PGMEA in a ratio of 0.7,
0.5, and 1.5 based on the molar ratio. Next, the temperature of the
mixture is increased to about 100.degree. C. and _ wt % of an
initiator (AIBN) based on the total amount of monomer is added and
reacted for 5 hours, while maintaining the above temperature. Next,
2 weight % of aniline based on 100 weight % of the total functional
monomer is added to the reaction solution and left for 1 hour.
Finally, when the reaction is completed, the used solvent is
removed by vacuum distillation and a yellow colored solid is
obtained. The synthesized polymer resin binder has a chemical
structure represented by Formula 2.
##STR00001##
[0079] In Formula 2, X has a molar ratio from 0.3 to 3.0, Y has a
molar ratio from 0.2 to 2.5, and Z has a molar ratio from 0.3 to
3.0. However, as desired, at least two kinds of each functional
monomer can be used. This will be described later in more detail.
Also, when PGMEA is used as a polymerization solvent, the solvent
need not be removed by vacuum distillation as PGMEA can be used in
a subsequent process for producing a pigment dispersion. Thus the
synthesized polymer resin binder solution can be directly applied
to the next process, thereby reducing the number of processes.
[0080] In a second exemplary embodiment of synthesis example,
synthesis of a polymer resin binder having an intensified polarity
structure will be described.
[0081] The solid structure and polarity of the polymer resin binder
can be adjusted according to the physical and chemical properties
of the pigment which is applied as described above, depending on
the kinds and/or the molecular weights of the functional monomers
used. For example, when 2-hydroxy methacrylate is used instead of
methyl methacrylate which has a lower molecular weight, the solid
structure and property of the binder becomes polar. Thus when the
polymer resin binder is used in combination with a pigment having a
strong polarity, the dispersion property and the dispersion
stability of the polymer resin binder are likely to increase. The
synthesized polymer resin binder has a chemical structure
represented by Formula 3.
##STR00002##
[0082] In Formula 3, the molar ratio of X is 0.3 to 3.0, the molar
ratio of Y is 0.2 to 2.5, and the molar ratio of Z is 0.3 to 3.0.
However, as desired, two or more kinds of each functional monomer
can be used. This will be described in more detail later. The
reaction solvent which is used in synthesis may be PGMEA or other
aprotic organic solvent.
[0083] When a polymer resin binder having a chemical structure
represented by Formula 3 is synthesized, 2.5 weight % of
N-ethylaniline based on 100 weight % of the total functional
monomer is added to complete the reaction. When the reaction is
completed, the used solvent is removed by vacuum distillation and a
yellow colored solid is obtained.
[0084] In a third exemplary embodiment, synthesis of a polymer
resin binder having a weakened polarity structure will be
described.
[0085] Monomers styrene, butyl methacrylate, and methacrylate acid
are mixed with diglyme in a ratio of 1.5, 0.5, and 0.3,
respectively, based on the molar ratio. Next, the temperature of
the mixture was increased to about 80.degree. C. and then an
initiator (AIBN) was added and reacted for 4 hours while
maintaining the above temperature. Next, 1.5 weight % of
2-ethylhexyl amine based on 100 weight % of the total functional
monomer was added to the reaction solution to complete the
reaction. The synthesized polymer resin binder has a chemical
structure represented by Formula 4 below. In this case, the polymer
resin binder has a reduced polarity, and when mixed with a pigment
having a relatively small polarity, the polymer resin binder can
have a good property.
##STR00003##
[0086] In Formula 4, the molar ratio of X is from 0.3 to 3.0, the
molar ratio of Y is 0.2 to 2.5, and the molar ratio of Z is 0.3 to
3.0. However, where desired, two or more kinds of each functional
monomer can be used. More will be described about this later. When
the synthesized polymer resin binder is used in an organic solvent,
the amount of the methacrylic acid is half the amount used in an
aqueous solution to obtain a useful polymer.
[0087] In a fourth exemplary embodiment, synthesis of a polymer
resin binder having a structure formed of a monomer only having an
affinity for pigment and a monomer having an affinity for solvent
will be described.
[0088] Monomers styrene and acrylic acid are mixed in a molar ratio
and added to a solvent. Next, the temperature of the mixture is
increased to 100.degree. C. and an initiator (AIBN) is added and
the mixture is reacted for 5 hours, while maintaining the
temperature. Next, 2.4 weight % of morpholine based on 100 weight %
of the total monomer is added to the reaction solution to complete
the reaction. When the reaction is completed, the used solvent is
removed by vacuum distillation, thereby obtaining a white solid.
The synthesized polymer resin binder has a chemical structure
represented by Formula 5 below.
##STR00004##
[0089] In Formula 5, the molar ratio of X is from 0.3 to 5, and the
molar ratio of Y is from 0.3 to 5, and more specifically X is from
2 to 3 and Y is from 1.5 to 2. The synthesized polymer resin binder
has a chemical structure represented by FIG. 5.
[0090] Hereinafter, a pigment dispersion containing the above
described polymer resin binder will be described in detail.
[0091] The pigment dispersion of inkjet ink for a color filter
according to the present embodiment comprises a pigment, dispersion
agent, and surfactant in each polymer resin binder or in a binder
mixture of two or three kinds of the polymer resin binders.
[0092] The pigment dispersion can also comprise multiple types of
polymer resin binder. When multiple types of polymer resin binder
are mixed to manufacture a pigment dispersion, the amount of each
type of the binder may be 5-95 weight % based on the total amount
of binder. In an embodiment, the total amount of the polymer resin
binder used is 20-150 weight % based on 100 weight % of the total
used pigment.
[0093] The pigment is pulverized to fine particles and supplied in
the form of powder and air trapped on the surface of the pigment
particle is discharged by mixing the pigment with the dispersion
agent and agitating the mixture. Thus, when the air is released
from the surface of the pigment particle, the solvent can readily
permeate the surface of the pigment particle, which is known as a
wetness effect and this is the characteristic of the dispersion
agent. In an embodiment, the pigment may be at least one selected
from the group of pigments consisting of red 254, red 177, blue
15:6, yellow 150, yellow 139, yellow 138, and violet 23, but is not
limited to this.
[0094] The dispersion agent may be EFKA 4046 and/or 4047 available
from Efka, a division of Ciba Specialty Chemicals; Solsperse.RTM.
32500 and/or Solsperse.RTM. 24000 available from Noveon;
DisperBYK.RTM. 161 and/or DisperBYK.RTM. 163, available from
BYK-Chemie; and the like, which are commercially available. The
amount of the dispersion agent used may be 0.1-30 weight %,
specifically 1-10 weight %, based on 100 weight % of the total
pigment.
[0095] The surfactant may be a fluoric material. In an exemplary
embodiment, the fluoric surfactant may be 3M.TM. Novec.TM. FC-4434
or FC-4430 available from 3M Corporation. When a fluoric surfactant
is added, the dispersion property is improved and the dispersion
stability is improved. The optimum amount of fluoric surfactant
used can be decided in consideration of the kind of the polymer
resin used, and can be 0.01-2 weight %, more specifically 0.1-0.5
weight %, based on 100 weight % of the total pigment.
[0096] It is desirable that the pigment is dispersed when used. For
pigments used in various components of electronic devices, highly
functional, low viscosity pigment dispersions are both useful and
desirable. The pigments used in electronic components should be
useful in forming a thin film, and therefore when using an
application method to form the thin film such as, for example, a
nozzle coating method or roll coating method, ejection properties
of the pigment must be sufficient to provide uniform thin film
coating properties. Accordingly, a high viscosity pigment
dispersion cannot form a thin film readily, and the ejection
property thereof is not adequate. Thus a high viscosity pigment
dispersion is not appropriate for electronic devices.
[0097] Color filter photoresists (photosensitive medium) used in
the manufacture of a color filter for a liquid crystal display
device therefore desirably comprise a low viscosity pigment
dispersion.
[0098] The pigment dispersion must have good heat resistance to
high temperature, chemical resistance, and mechanical property
which maintains a mechanical strength above a set value after
hardening. For example, it is required a high functional pigment
dispersion which can maintain stability of a disperse system in a
high temperature process where the pigment dispersion is hardened
at 220.degree. C. for more than 1 hour during the manufacture of a
color filter.
[0099] Also, with increased numbers of properties needed for a
liquid crystal display device, the properties of the pigment
dispersion for a color filter must also correspondingly increase to
provide the properties. That is, the conventional pigment
dispersion is generally used in the manufacture of a pigment
dispersion for a spin coating with limits, but as liquid crystal
display devices become larger than conventional liquid crystal
display devices, other coating methods such as, for example, a
blade, roll, nozzle coating method can be used instead of or in
addition to spin coating methods. The pigment dispersions have
properties which are appropriate for each coating method as
needed.
[0100] Additional chemical materials are added to the pigment
dispersion to be manufactured as inkjet ink for a color filter or a
photosensitive agent, and accordingly, the pigment dispersion is
required to have chemical resistance. The typical chemical
materials added to the pigment dispersion are photosensitive agent,
polymer resin binder, surfactant, monomer, viscosity controller,
and the like.
[0101] When the pigment dispersion is bonded with the additives
physically and/or chemically, the disperse system is destroyed, and
the pigment in binder is hardened and layer separation occurs. Thus
the value of the pigment dispersion as a product decreases and can
lead to defects in the final product, a liquid crystal display
device, creating a considerable amount of product loss and low
product yield.
[0102] Thus, the pigment dispersion must have good chemical
resistance and high mechanical strength. However, the properties of
the conventionally commercialized products are limited and is thus
difficult to disperse various kinds of pigments.
[0103] In the pigment dispersion according to the present
embodiment, the pigment can be dispersed at about 15 weight % based
on 100 weight % of the total pigment dispersion, and the viscosity
thereof is low as about 20 cP (centipoise) and can be directly
applied to a photosensitive resin for a color filter or an inkjet
ink for a color filter.
[0104] For the pigment dispersion to have the above described
properties, the polymer resin binder which is used in the
manufacture of the pigment dispersion as described above is
prepared so that it can provide one or more of the desired
properties when used with the pigment dispersion. In an exemplary
embodiment, the pigment dispersion according to the present
embodiment is manufactured by the following process.
[0105] First, the polymer resin binder is mixed with a pigment and
solvent present in predetermined amounts according to the
limitations disclosed hereinabove. Next, the mixture undergoes a
wetness process and is pulverized using a bead mill or a micro
fluidizer. The result is a low viscosity pigment dispersion. Also,
in order to increase the dispersion efficiency, two or three
polymer resin binders can be mixed and used.
[0106] Meanwhile, various additives are added to the above
described pigment dispersion agent to manufacture an inkjet ink for
a color filter. The inkjet ink for a color filter can be
manufactured by adding a polymer resin binder to the pigment
dispersion.
[0107] In a specific embodiment, an inkjet ink for a color filter
comprises a pigment dispersion, a solvent, polymer resin binder,
surfactant, initiator, and other additives.
[0108] The solvent used in the manufacture of an inkjet ink affects
the ejection property and ejection stability of the inkjet ink. The
solvent used have a boiling point of greater than or equal to
150.degree. C., however when the boiling point is greater than
300.degree. C., some solvent remains behind during hardening and
can be a factor causing pixel deterioration. In an embodiment, the
boiling point of the solvent is 200-270.degree. C.
[0109] The solvent, the surfactant, the initiator, and other
additives useful for the inkjet ink are as described hereinabove,
and the description thereof will not be repeated.
[0110] In an embodiment, a method of making an inkjet ink comprises
mixing the pigment, the dispersion agent, the surfactant, and a
polymer resin binder comprising an amine based organic material. In
a specific embodiment, the polymer resin binder is added to the
pigment dispersion. In an exemplary method, the inkjet ink is
manufactured by adding a pigment dispersion to a reactor with an
agitator and adding solvent, polymer resin binder, surfactant,
initiator, and other additives, and agitating the mixture.
[0111] The present invention will be described in greater detail
with reference to following examples. The following examples are
for illustrative purposes and are not intended to limit the scope
of the invention.
EXAMPLES
[0112] Manufacture of Polymer Resin Binder
Example 1
[0113] Benzyl methacrylate (0.07 mol, 12.3 g), methyl methacrylate
(0.07 mol, 7.0 g), and methacrylic acid (0.075 mol, 6.5 g) were
mixed in 100 g of PGMEA and a small amount of nitrogen was bubbled
through to deoxygenate the mixture. The temperature of the mixture
was increased to 80.degree. C. and 0.28 g of an initiator (AIBN)
was added and reacted at 80.degree. C. for 5 hours. During
reaction, nitrogen bubbling was continued to prevent contact with
oxygen so that the generated radical did not quench. Thereafter,
0.52 g of aniline was added to the reaction solution. 1 hour after
adding aniline, the temperature was slowly reduced to an ambient
temperature. Thus a polymer resin binder solution containing about
20% solid content was obtained.
Example 2
[0114] A polymer resin binder containing about 20% solid content
was obtained in the same manner as in Example 1 except that styrene
(0.07 mol, 7.3 g) instead of benzyl methacrylate and 1.1 g of
pyrrolidine instead of aniline were added to 80 g of PGMEA.
Example 3
[0115] A polymer resin binder containing about 20% solid content
was obtained in the same manner as in Example 1 except that
2-hydroxy ethyl methacrylate (0.07 mol, 9.1 g) instead of methyl
methacrylate, and 0.7 g of N-ethyl aniline instead of aniline were
added to PGMEA.
Example 4
[0116] Benzyl methacrylate (0.04 mol, 7.0 g), styrene (0.03 mol,
3.1 g), methyl methacrylate (0.07 mol, 7.0 g), and methacrylic acid
(0.15 mol, 12.9 g) were mixed in 68 g of PGMEA and a small amount
of nitrogen was bubbled through to deoxygenate the mixture. Then
the temperature of the mixture solution was increased to 90.degree.
C. and 0.28 g of an initiator (AIBN) was added and the mixture was
reacted for 5 hours at a temperature of 90.degree. C. During
reaction, nitrogen bubbling was continued to prevent contact with
oxygen in the air so that the generated radical did not quench.
Then 0.85 g of aniline was added to the reaction solution. 1 hour
after adding aniline, the temperature was slowly reduced to an
ambient temperature. Thus a polymer resin binder solution
containing about 20% solid content was obtained.
Example 5
[0117] Benzyl methacrylate (0.04 mol, 7.0 g), styrene (0.03 mol,
3.1 g), methyl methacrylate (0.05 mol, 5.0 g), and methacrylic acid
(0.03 mol, 2.6 g) were mixed in 60 g of PGMEA and a small amount of
nitrogen was bubbled through to deoxygenate the mixture. The
temperature of the mixture was increased to 80.degree. C. and 0.35
g of an initiator (AIBN) was added and reacted for 5 hours while
maintaining a temperature of 100.degree. C. During reaction,
nitrogen bubbling was continued to prevent contact with oxygen in
the air so that the generated radical did not quench. Then 1.0 g of
morpholine was added to the reaction solution. 1 hour after adding
the morpholine, the temperature was slowly reduced to an ambient
temperature.
Example 6
[0118] A polymer resin binder was obtained in the same manner as in
Example 5 except that benzyl methacrylate was not added but styrene
(0.07 mol, 7.3 g) was added and 0.8 g of triethylamine was added
instead of morpholine.
Example 7
[0119] Styrene (0.1 mol, 10.4 g) and acrylic acid (0.1 mol, 7.3 g)
were mixed in 60 g of PGMEA and a small amount of nitrogen was
bubbled through to deoxygenate the mixture. The temperature of the
mixture was increased to 80.degree. C. and 0.25 g of an initiator
(AIBN) was added and reacted for 5 hours at 80.degree. C. During
reaction, nitrogen bubbling was continued to prevent contact with
oxygen in the air so that the generated radical did not quench.
Then 0.75 g of aniline was added to the reaction solution. 1 hour
after adding aniline, the temperature was slowly reduced to an
ambient temperature.
[0120] Manufacture of Pigment Dispersion
Example 8
[0121] 15 g of pigment red 254 (available from Ciba Specialty
Chemicals, Switzerland) and 1.0 g of Solsperse.RTM. 32500, 0.2 g of
Novec.TM. FC-4434, 78.8 g of PGMEA were mixed with 3.0 g of the
polymer resin binder solution synthesized in Example 1 and 2.0 g of
the polymer resin binder solution synthesized in Example 3 and this
solution was agitated properly for 2 hours and wetted. Then 300 g
of sand was added and pulverized for 5 hours at 3,000 rpm using a
disk having a diameter of 7 cm. After pulverization was completed,
the sand was removed using a sieve. Thus a red pigment dispersion
having an average particle size of 75 nm was obtained.
Example 9
[0122] 10 g of red pigment 254 was mixed properly with 50 g of the
polymer resin binder solution synthesized in Example 5 and agitated
for 1 hour. Here, 100 g of zirconia beads of 0.3 mm were added and
the mixture was pulverized for 3 hours at 3,000 rpm using a disk
having a diameter of 7 cm. After pulverization was completed, the
beads were removed using a sieve. Thus a red pigment dispersion
having an average particle size of 80 nm was obtained.
Comparative Example 1
[0123] A pigment dispersion was obtained using a commercial
dispersion agent EFKA 4046, as disclosed in U.S. Pat. No.
6,696,207.
[0124] 6 g of EFKA-466 and 15 g of red pigment 254, 79 g of PGMEA
were mixed and this mixture was agitated properly for 2 hours and
wetted. Here, 300 g of sand was added and the mixture was
pulverized for 5 hours using a disk having a diameter of 7 cm at
3,000 rpm. After pulverization was completed, a sieve was used to
remove the sand. Thus a red pigment dispersion having an average
particle size of 78, nm was obtained.
[0125] Manufacture of Inkjet Ink
Example 10
[0126] 20 g of polymer resin binder synthesized in Example 1, 5 g
of dipentaerythritol pentaacrylate, which is a functional monomer,
and 0.2 g of AIBN, which is a thermal initiator, were mixed with
44.8 g of diethyleneglycol monobutyl ether acetate, an organic
solvent. Here, 30 g of pigment dispersion manufactured in Example 7
was slowly added and agitated. Then, the mixed solution was passed
through a 10-micrometer filter to remove coarse particles so the
filtered solution could be used to manufacture inkjet ink for a
color filter.
[0127] Test of Average Particle Size and Stability Test of the
Manufactured Pigment Dispersion According to Time
[0128] The pigment dispersion is tested for dispersion stability to
ensure the particles do not stick to each other and precipitate,
and so layers of the pigment dispersion do not separate. The
pigment dispersion is observed over time, and as time passes, the
size and viscosity of the particle should show little change.
Change in the size and viscosity of the particle is undesirable and
denotes that the disperse system is unstable and thus unusable,
meaning that the pigment dispersion cannot perform a basic function
as a pigment dispersion.
[0129] The dispersion stability test is to observe the time passage
stability using a particle size analyzer ("PSA"), and in order to
observe within a short time, an accelerated test was performed. The
accelerated stability test was performed at 60.degree. C. for 4
hours and at -10.degree. C. for 4 hours, and this was repeated 4
times to observe the change in particle size.
[0130] The results of the accelerated stability test are listed in
Table 1 below. Here, the pigment dispersions of Example 8 and
Comparative Example 1 were used.
TABLE-US-00001 TABLE 1 Example 8 Comparative Example 1 Content of
Binder of 3.0 wt % EFKA 4046 6.0 wt % components Example 1 in the
Binder of 2.0 wt % Red 15.0 wt % pigment Example 3 pigment 254
dispersion Solsperse .RTM. 1.0 wt % Solvent 79.0 wt % 32500 (PGMEA)
Red pigment 254 15.0 wt % Novec .TM. 0.2 wt % FC-4434 Solvent 78.8
wt % (PGMEA) Average 75 nm 78 nm particle size before stability
test Average 79 nm 82 nm particle size after stability test
[0131] The average particle size and stability according to time of
the pigment dispersion will be examined with reference to Table
1.
[0132] In the case of the pigment dispersion of Example 8, the
average particle size was 75 nm and 79 nm before and after the
stability test, respectively. On the other hand, in the case of
Comparative Example 1, which is a conventional pigment dispersion,
the average particle size was 78 nm and 82 nm before and after the
stability test, respectively. Accordingly, the average particle
size of the pigment dispersion in the present invention was smaller
by about 3 nm than that in the conventional art both before and
after the stability test. Accordingly, the dispersion property of
the pigment dispersion according to an embodiment of the present
invention is better than the conventional pigment dispersion.
[0133] Also, the average particle size before and after stability
test according to time both increase by about 4 nm. Thus Table 1
shows that the pigment dispersion according to the present
embodiment has a good dispersion property and the same degree of
dispersion stability as that of the conventional art. Accordingly,
as evident from the results of the test, there is no difficulty in
using the pigment dispersion according to the present invention
commercially and the dispersion property thereof is better compared
to the conventional art.
[0134] Test of Election Property and Ejection Stability of the
Manufactured Inkjet Ink
[0135] An ejection test was performed using a Litrex inkjet system
in which a spectra inkjet head was mounted. Stable ejection without
clogging of a head during ejection for a predetermined period of
time without measurable change in the amount of ejected ink was
considered as the test standard.
[0136] The test result is listed in Table 2. The inkjet ink
manufactured in Example 10 was used. However, the present invention
is not limited to this but can be manufactured by combination of
the above described pigment dispersion, a polymer resin binder, a
hardening monomer, a heat initiator, a solvent, and the like.
TABLE-US-00002 TABLE 2 Example 10 Ejection stability Pigment
dispersion manufactured in Example 7 30 wt % During ejection for 3
Polymer resin binder manufactured in Example 1 20 wt % continuous
hours, ink was Hardening monomer (Dipentaerythritol 5 wt % stably
ejected without any pentaacrylate) change as the droplet of the
Thermal initiator (AIBN) 0.2 wt % initial ejection ink and the
final Organic solvent (Diethyleneglycol monobutyl ether 44.8 wt %
ejection ink both had a acetate) diameter of 100 .mu.m.
[0137] As evident from Table 2, the inkjet ink according to the
present embodiment has a very good ejection property and ejection
stability.
[0138] Test of Degree of Condensation of Inkjet Ink Coated on a
Color Filter of a Liquid Crystal Display Device
[0139] The effect of adding an amine based organic material was
observed experimentally.
[0140] FIG. 2A is a photograph showing the degree of condensation
of an inkjet ink not containing amine based organic material used
to form a conventional color filter. FIG. 2B is a photograph
showing the degree of condensation of an inkjet ink containing an
amine based organic material for a color filter according to an
embodiment of the present invention.
[0141] In FIGS. 2A and 2B, (R), (G), and (B) denote red, green, and
blue sub-pixels of a color filter, respectively.
[0142] Referring to FIGS. 2A and 2B, when an amine based organic
material was not added, the condensation of the particles was
prominent, and when an amine based organic material was added, the
condensation of the particles was remarkably reduced.
[0143] Hereinafter, the effect of the amine based organic material
to the condensation of ink particles will be described in detail
with respect to the attached drawings.
[0144] First, an inkjet ink is coated inside each sub-pixel of a
liquid crystal display device. Then, a solvent included in the
inkjet ink is dried and the amount of solid content of the inkjet
ink increases. Here, when an amine based organic material is not
added, the dispersion balance of the dispersion agent, the polymer
resin binder, and the pigment shows defects, and as illustrated in
FIG. 2A, condensation of the ink particles occurs and the inkjet
ink becomes opaque.
[0145] However, when an amine based organic material is added, the
amine based organic material physically bonds with acid and amine
which are present in the dispersion agent or in the polymer resin
binder and thus improves the dispersion stability. Accordingly, as
illustrated in FIG. 2B, the inkjet ink having the amine based
organic material added prevents the condensation of ink
particles.
[0146] According to an embodiment of the present invention, a
polymer resin binder which can improve the dispersion property and
dispersion stability of the pigment when added during the
manufacture of an inkjet ink for a color filter of a liquid crystal
display device is provided.
[0147] Also, according to an embodiment of the present invention, a
polymer resin binder which is used to manufacture an inkjet ink for
a color filter of a liquid crystal display device to improve the
ink ejection property and ejection stability from an inkjet head is
provided.
[0148] While the present invention has been particularly shown and
described with reference to exemplary embodiments thereof, it will
be understood by those of ordinary skill in the art that various
changes in form and details may be made therein without departing
from the spirit and scope of the present invention as defined by
the following claims.
* * * * *